Python 3.6 ordered set using a Dict

ordered_set.py

'''
In python 3.6 dictionaries are ordered:

"The order-preserving aspect of this new implementation 
is considered an implementation detail and should 
not be relied upon."

But let's face it, we're going to use it and it is
going to become a consistent feature.

This is an example of using a Dict to act like an OrderedSet - ordered, unique values.

It's way cooler than the standard old `OrderedDict` type.
'''

my_dict = {'A unique value': None, 'another unique value': None}
list(my_dict.keys())
['A unique value', 'another unique value']